AT&T is planning to conduct trial runs of LTE later this year and to commercially launch its LTE network sometime in 2011. The carrier says that Alcatel-Lucent and Ericsson will be the main suppliers for its Radio Access Network Domain and that their equipment will be deployed at cell sites along AT&T's current network.

But while AT&T has begun preparing for the launch of its 4G network next year, the company has also been aggressively promoting upgrades to its current 3G HSPA network. AT&T says that a big part of its wireless network upgrade will come through its transition to HSPA 7.2 technology that the company expects will cover 90% of its 3G network by the end of 2011. HSPA 7.2 is a variation of the GSM-based HSPA technology that has a peak speed of 7.2Mbps, although AT&T cautions that most users are unlikely to see data rates approaching theoretical peak speeds.

In addition to switching its 3G network to HSPA 7.2, AT&T is also hoping to boost network capacity by utilizing more spectrum on the 850MHz band. The company is hoping that deploying its 3G network over the 850MHz spectrum will solve some of the big capacity and propagation problems it has encountered in major markets such as New York and San Francisco.

Rival carrier Verizon is expected to be the first U.S. carrier to commercially deploy LTE, as it plans to launch 4G services in about 30 major markets in the United States throughout 2010. Verizon late last year started trialing LTE in both Boston and Seattle, and in its initial trials with partner Vodafone, Verizon has achieved peak speeds of 60Mbps on its LTE network.